package main

import (
	"fmt"
	"io/ioutil"
)

func testSwitch(score int) string {
	switch {
	case score < 0 || score > 100:
		panic("6666")
	case score < 60:
		return "F"
	case score < 80:
		return "B"
	case score < 100:
		return "A"
	}
	return "666"
}

func main() {
	const filename = "abc.txt"
	if file, err := ioutil.ReadFile(filename); err != nil {
		fmt.Println(err)
	} else {
		fmt.Printf("%s", file)
		fmt.Println()
	}
	fmt.Println(testSwitch(-1))
}
